This invention relates to a high-pressure turbine of a gas-turbine engine.
More particularly, this invention relates to a high-pressure turbine of a gas-turbine engine with a main gas duct internal seal. Specifically, a turbine disk which carries the rotor blades is provided. Furthermore, the high-pressure turbine comprises, as usual, stator blades attached to a stator ring. A lateral wheel cavity is formed between the turbine disk and the stator ring.
On high-pressure turbines, the lateral wheel cavity must always be sealed appropriately against the main gas duct to enable cooling air for the cooling of the rotor blades to be fed via the lateral wheel cavity. The known designs of sealing arrangements have different overlaps between the platforms of the rotor blades and those of the stator blades. Here, the size of the gaps is such that the pressure of the main gas duct is essentially imparted to the lateral wheel cavity. With simple seal designs, the pressure disadvantageously is incapable of feeding a leading-edge cooling film for the rotor blades. To overcome these disadvantages, solutions are provided in the state of the art in which the lateral wheel cavity is divided into individual chambers by means of different seals. In these solutions, the mass flow for blade cooling is usually provided from a radial inner chamber, while a radial outer chamber primarily serves to prevent hot gas from flowing in from the main gas duct.
Here, it is disadvantageous that, in particular, the outer chamber, which is located at one of the hottest zones of the high-pressure turbine outside the main gas duct, is flushed by only a very low mass flow. Furthermore, this mass flow is additionally heated on its passage through a seal. All these factors result in a high thermal load of the turbine disk (disk rim of the first stage of the high-pressure turbine). This, in turn, entails a severe limitation of the life of the turbine disk.